Field of the Invention
The present invention relates to a ratchet type one-way clutch that uses a ratchet (pawl member) for a lock mechanism. The ratchet type one-way clutch is used for a power transmission section, etc. in automobiles, agricultural machinery, construction machinery, machine tool and so on and has a function such as back stop.
Description of the Related Art
A one-way clutch used in an automatic transmission generally is provided with an outer race and an inner race that rotate relatively to each other and configured to transmit the rotational torque only in one direction by allowing sprags, rollers and others, which transmit the torque between the outer race and the inner race, to engage with a cam surface provided on a track surface of the outer race or the inner race. At the same time, the one-way clutch is configured to run idle in an opposite direction.
Among such one-way clutches, there is a ratchet type one-way clutch that uses a ratchet as a torque transmission member which transmits torque between the outer race and the inner race (see Japanese Patent Application Laid-Open No. 2001-208104). The ratchet type one-way clutch includes: an outer race having a pocket on an inner circumference thereof; an inner race arranged coaxially with the outer race and having a notch on an outer circumference thereof; a pawl member housed in the pocket and engaged with the notch of the inner race so as to lock the one-way clutch, thereby allowing torque to be transmitted between the inner race and the outer race; and a spring for urging the pawl member to the inner race.
When the ratchet type one-way clutch thus configured rotates in one direction, the pawl member slides freely from the outer circumference of the inner race, which results in that the outer race and the inner race run idle relatively to each other. Then, in an attempt of the one-way clutch to rotate in the other direction, the pawl member engages with the notch to lock the one-way clutch. This enables the torque to be transmitted between the inner race and the outer race.